GB2050439A - Method of and apparatus for starting and stopping an open end spinning machine - Google Patents

Description

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SPECIFICATION

Method and apparatus for starting and stopping an open end spinning machine

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This invention relates generally to an open end spinning machine, and more particularly to the prevention of the occurrence of snarls in the yarn end present in a yarn take-up tube at the time when the 10 spinning machine stops or starts to operate.

Generally, in an open end spinning machine such as, for example, described in U.S. Patent 3,354,626, each spinning unit includes means for feeding individually opened fibers into a spinning rotor, in which 15 subatmospheric pressure is produced by rotation thereof. The opened fibers are formed into a yarn in the spinning rotor. The yarn is transported from the spinning rotor by a take-up means including a yarn take-up tube and yarn take-up rollers and wound on 20 a bobbin by a winding means. Also, in the above open end spinning machine, each of the fiber feeding means, yarn take-up means and yarn winding means is mounted on a separate driving shaft and a single motor drives these separate driving shafts 25 through a rotation transmission mechanism including trains of gears. This motor also drives an endless belt, which is in frictional contact with spindles of the spinning rotors to rotate the same.

When the spinning machine is stopped, the fiber 30 feeding means is first stopped to discontinue the supply of fibers to the spinning rotor, then take-up roller and winding roller are then stopped at a time when the yarn end resulting from breakage of the yarn still remains in the yarn take-up tube which 35 undergoes the suction effect of the subatmospheric pressure in the spinning rotor. Finally, all the spinning rotors are stopped. On starting, all the spinning rotors start to rotate simultaneously, the yarn take-up rollers and winding rollers are then rotated in a 40 reverse direction to push the yarn ends from the take-up tubes into the spinning rotors, while the fiber feeding means are operated to supply the opened fibers into the spinning rotors thereby to allow them to be twisted into the reversed yarn ends. Thereafter, 45 the take-up rollers and winding rollers are rotated in a normal, yarn winding direction.

With this stopping method, the rotation of the spinning rotors continues for a predetermined period of time even afterthe take-up rollers have 50 stopped, and the rotating rotors can impose the suction effect thereof upon the yarn ends in the yarn take-up tubes. This causes each yarn end to be untwisted between the associated spinning rotor and take-up rollers so that the occurrence of snarls in -55 the yarn end can be prevented to some extent. However, where the yarn end has been given a strong twist, the afore-mentioned suction effect of the spin-- ning rotor may not satisfactorily prevent the yarn end from being snarled afterthe stop of rotation 60 thereof and therefore the yarn end may shrink upwardly out of the yarn take-up tube. In such case, even when the spinning rotor is rotated before the rotation of the take-up roller and winding roller starts in the reverse direction, it is not possible to introduce 65 the yarn end into the take-up tube and hence to the spinning rotor by the suction effect of the latter. Moreover, in the spinning machine as discussed above, since the untwisting of the yarn end is intended to be effected between the spinning rotor 70 and the yarn take-up rollers, the length over which the yarn end is untwisted, is such that yarn quality is adversely affected.

It is therefore a principal object of this invention to provide a method and apparatus for starting and 75 stopping an open end spinning machine, which can significantly prevent the occurrence of snarls in the yarn end regardless of the degree of twist of the yarn and can limitthe untwisted length of the yarn to a favourable value.

80 A control apparatus according to this invention includes, in addition to a power on-off switch, switches for stopping and starting an open end spinning machine. When the spinning machine is stopped, the stop switch is pushed down to stop 85 each of the yarn taking up means, yarn winding means, and the supply of fibers to a spinning rotor, when yarn breakage occurs in the spinning rotor. The yarn end resulting from the breakage is held by a yarn holding lever before it moves out of a yarn 90 take-up tube extending into the spinning rotor, the spinning rotor is then stopped after a predetermined period of time, during which the yarn end held by the yarn holding lever undergoes the suction effect of a subatmospheric pressure produced in the spinning 95 rotor so that the yarn end is untwisted in the yarn take-up tube thereby preventing the occurrence of the snarling phenomenon whereby the yarn end shrinks up and comes out of the yarn take-up tube.

On starting, the start switch is operated to produce 100 a signal indicating the re-starting of the spinning machine. The holding of the yarn end by the yarn holding lever continues until the spinning rotor reaches a sufficient speed to produce a subatmospheric pressure capable of stretching out the yarn 105 end so that the latter can be prevented from being snarled in the yarn take-up tube. The yarn holding lever has a free end positioned adjacent to the yarn outlet end of the yarn take-up tube and the yarn end is adapted to be held by this end of the yarn holding 110 lever so that the length ofyarn untwisted bythe suction effect of the spinning rotor can be reduced as compared with that of the prior art. This achieves good results with regard to yarn quality.

The invention illustrated byway of example in the 115 accompanying drawings, wherein:—

Fig. 1 is a fragmentary schematic view showing a portion of a prior art spinning machine to which this invention is applicable;

Fig. 2 is a perspective view of a yarn holding 120 device employed in an embodiment of this invention; and

Figs. 3A and 3B illustrate a suitable electric circuit for operating an apparatus in accordance with this invention.

125 Referring to Fig. 1, there is shown a drive transmission mechanism of a prior open end spinning machine similartothat described in U.S. Patent 3,354,626 and this invention can be applied to such a spinning machine. Although only one spinning unit 130 is shown in Fig. 1, the spinning machine normally

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comprises a number of spinning units along each side of the spinning machine, and yarn ending operations are simultaneously effected in all the spinning units on starting the machine.

5 Each spinning unit comprises a spinning rotor 1 into which opened fibers are supplied and formed into a yarn 9, means for feeding a sliver or roving 35 from a can 34, means for opening the sliver 35 into the individual fibers and supplying them into the 10 spinning rotor 1, means fortaking up the yarn 9, and a winding roller 4 for winding the yarn 9 onto a bobbin 11. The feeding means comprises lower and upper feeding rollers 2 and 7 forming a nip therebetween, through which the sliver 35 is fed. The fiber 15 opening and supplying means comprises a combing roller 5 of well-known type. The take-up means 3 includes a lower take-up roller and an upper take-up roller driven by the lower roller. The spinning rotor 1 may be of eitherthe self-discharge type, wherein air 20 in the interior of the spinning rotor is discharged through openings 1a provided in the bottom of the spinning rotor due to its rotation, or the forced-discharge type, wherein air in the interior of the spinning rotor is discharged through an intake sys-25 tem (not shown) disposed outside of the spinning rotor. In any case, a subatmospheric pressure is produced in the interior of the spinning rotor 1 during rotation and the individual fibers opened by the combing roller 5 are thereby drawn into the interior 30 of the spinning rotor 1.

The take-up means includes a yarn take-up tube 1' disposed between the take-up roller 3 and the spinning rotor 1 so as to be in air communication with the latter. As is well known, the individual fibers are 35 twisted into the yarn end in the spinning rotor 1 and the resultant yarn 9 is taken up from the spinning rotor 1 through the take-up tube 1' by the take-up rollers 3. Although only one pair of take-up rollers 3 is shown, all the lowertake-up rollers in the number 40 of spinning units are mounted on a common driving shaft 10 mounted for rotation in the frame of the spinning machine. The winding roller 4, which has crossed grooves, is in driving relationship with the bobbin 11 to wind a package thereon in a cross wind-45 ing manner. All the winding rollers 4 of the spinning units are attached to a driving shaft 12 rotatably mounted in the machine frame and controlled by an electromagnetic brake MB2 in a manner as discussed below.

50 The driving shaft 12 is rotated through a train of gears 13,14 and 15 by the driving shaft 10 in the same direction as the shaft 10.

Also, all the sliver feed rollers 7 are mounted on a common driving shaft 8 connected through a sliver 55 feed electromagnetic clutch MC3 (hereinafter referred to as the "feed clutch") with a shaft 16' supporting a gear 16, which is driven through a train of gears 17,18,19 and 20 by an electric motor M and controlled by an electromagnetic brake MB1 as discussed 60 below. The shaft 10 for driving the takeup rollers 3 is connected through an electromagnetic clutch MC1 with a shaft 17' supporting the gear 17. The clutch MC1 is hereinafter referred to as the "reverse clutch" because the yarn is fed in a reverse direction when 65 the clutch MC1 is in engagement. To rotate the shaft

10 in a forward direction, the gear 18 supported by a shaft 18' is connected through an electromagnetic clutch MC2 and a train of gears 23,24 and 25 with the shaft 10. The gear 23 is mounted on the shaft 10 so as to be positioned between the reverse clutch MC1 and the gear 15. The gear 23 meshes with the intermediate gear 24, which meshes in turn with the gear 25 supported by a shaft 26. The shaft 26 is connected to a driven member of the clutch MC2. The clutch MC2 is hereinafter referred to as the "forward clutch", because the yarn is fed in a forward direction when it is in engagement.

Mounted around a pair of pulleys 30 and 31 is an endless belt 29, which is in driving relationship with all the spinning rotors 1 in a conventional manner so that all the spinning rotors 1 are simultaneously rotated in the same direction. The pulley 30 is driven through a train of gears 32,32', 33 and 20 by the motor M.

Therefore, it will be understood that in this embodiment all the spinning units are driven by the single motor M and their operation is controlled by controlling the motor M, forward clutch MC2, reverse clutch MC1, feed clutch MC3 and electromagnetic brakes MB1 and MB2 by means of a control apparatus 21. The apparatus 21 also controls yarn holding devices 6 each disposed adjacent to the respective take-up tube 1' and forming a part of the stopping and starting apparatus according to this invention.

Details of the yarn holding device 6 and the control apparatus are shown respectively in Fig. 2 and Figs. 3A and 3B. In Fig. 2, there is shown a yarn breakage sensing device, which is similar to that disclosed in British Patent 1,158,623 and also available as the yarn holding device 6. The sensing device includes a base plate 6a provided with a V-shaped guide notch 66, adjacent to which the upper end of the take-up tube 1' extends upwardly, and a yarn holding lever 6c pivotably connected with the base plate 6a. The yarn holding lever 6c is provided with oppositely extending plate-like arms 6e and 6/made of suitable known ferromagnetic material and associated respectively with an electromagnet SOLe and a permanent magnet 6g. When the magnet SOLe is energized, it attracts the arm 6e and causes the lever 6c to turn from a yarn holding position (shown in Fig. 2) into the righthandmost position (not shown). In the yarn holding position, the lever 6cabuts at its upper end 6d against an elastic support block &h to hold the yarn 9 therebetween. When the lever 6c turns toward the yarn holding position, the lower arm 6f is attracted by the permanent magnet 6g thereby to urge the lever 6c into the yarn holding position. This ensures that the lever 6c provides an increased pressure against the support block 6/? to firmly hold the yarn 9.

When the spinning machine is stopped, the fiber feeding means is first stopped to discontinue the supply offiberstothe spinning rotors in accordance with this invention. At that time, yarn breakage occurs in each of the spinning rotors or a lowering of tension of the yarn occurs due to the discontinuance of fiber supply and therefore the lever 6c is turned into the yarn holding position in which its end 6d elastically holds the yarn end cooperation with the

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support block 6fj before the yarn end moves out of the take-up tube 1'. On re-starting of the spinning machine, when the suction effect provided by the rotation of the spinning rotor attains a sufficient level 5 to preventthe occurrence of snarls in the yarn end in the take-up tube 1', the electromagnet SOLe is energized underthe control of the control apparatus 21 as described in detail hereinafter, whereupon the electromagnet SOLe attracts the upper arm 6e 10 against the action of the permanent magnet 6g, this causing the yarn end held by the lever 6c to be released.

A suitable form of the control apparatus 21 and its operation are described below in conjunction with 15 Figs. 3A and 3B.

The vertical lines labelled respectively with a plus symbol (+) and a minus symbol (-) represent the positive and negative sides of a source of current, and the various elements constituting the control 20 apparatus 21 in this embodiment of the invention are connected in the manner shown in Figs. 3A and 3B. A power on-off switch SW^ stop pushbutton SW2 and start pushbutton SW3 are in series with each other. These switches are in the on state, i.e., closed 25 during spinning operation of the spinning machine.

When the spinning machine is stopped, the stop pushbutton SW2 is turned off, with the pushbutton SW, and SW3 maintained in the on state whereupon a control relay CR1 is deenergized to open its nor-30 mally open contacts CR1-1 to CR1-5 and to close its normally closed contacts CR1-6. Because the contacts CR1-2 and CR1-3 are brought into the off state, an off timer DR for causing a delayed stop of the driving motor M starts to count a settime. Also, by 35 the opening of contacts CR1 -5, a relay CR3 is deenergized to open the normally open contacts CR3-2, whereby the supply clutch MC3 and supply brake MB1 both connected to the shaft 8 (Fig. 1) are brought into the off state and on state respectively, 40 stopping the supply of fibers. As a result, the yarn holding lever 6c, which has been maintained in a yarn sensing position between the yarn holding position shown in Fig. 2 and the righthandmost position by the tension of the yarn 9 during spinning opera-45 tion, it turned to the yarn holding position by the assistance of the permanent magnet 6g attracting the lower arm 6f thereto when the yarn breakage or reduction of yarn tension occurs due to the discontinuance of fiber supply. Thus, the yarn can be elasti-50 cally held between the end 6d of the yarn holding lever 6c and the elastic support block 6ft so that the occurrence of snarls can be prevented. On the other hand, since the normally closed contacts CR1-6 of the relay CR1 are closed simultaneously with the 55 opening of the normally open contacts of the same, a timer or time counter TR13 for a delaged operation of the electromagnetic brake MB2 associated with '• the winding shaft 12 starts to count to a settime. When it counts to the settime, the normally closed 60 contacts TR13-1 cause a control relay CR4 to be deenergized, whereupon the normally open contacts CR4-1 are opened to bring the forward clutch MC2 into the off state and the normally closed contacts CR4-2 are closed to bring the winding shaft brake 65 MB2 into the on state. Thus, both the take-up rollers

3 and winding rollers 4 are stopped. At that time, the driving motor M continues to rotate and accordingly the spinning rotors also rotate thereby to cause the yarn ends in the take-up tubes 1' to undergo the suction effect thereof. However, when the timer DR for the delayed stop of the motor M, which timer has started to count to the settime through the push down of the stop pushbutton SW2, counts to the set time, its normally closed contacts DR-1 are opened to deenergize a motor switch relay MS thereby to open contacts MS-1, MS-2 and MS-3. Thus, the driving motor M is stopped, resulting in delayed stopping of the spinning rotors 1.

When the spinning machine is re-started from the above-discussed stop condition, both the start and stop switches SW3 and SW2 are operated to close the circuit. Because of this, the control relay CR1 is deenergized to close the normally open contacts CR1 -1, whereupon a timer TR1 starts to count to a set time, at which the electromagnets SOLe are energized to attract the upper arms 6e of the yarn holding levers 6c thereto to maintain the yarn holding levers 6c in their righthandmost position. The contacts CR1-2 and CR1-3 are closed simultaneously to close the normally closed contacts DR-1 of the off timer DR, whereby the motor start relay MS is energized to close the contacts MS-1, MS-2 and MS-3. Thus, the driving motor M is operated and accordingly the spinning rotors 1 start to rotate. The settime of the timer TR1, which becomes operative simultaneously with the commencement of rotation of the spinning rotors 1, is so selected as to correspond to a period of time, at least by the end of which the spinning rotors 1 are caused to attain a sufficient speed to apply the suction effect thereof to the yarn ends in the take-up tubes 1'thereby to satisfactorily stretch out the same.

Therefore, it will be understood that no snarls would occur in the yarn ends even afterthey are released from the associated holding levers 6c by the attraction of the magnets SOLe on the upper arms 6e of the yarn holding levers 6c when the set time of the timer TR1 elapses.

Moreover, the contacts CR-4 of the relay CR1 are closed simultaneously to cause a timer TR2 to start to count to a settime, at which the take-up rollers and winding rollers are to be rotated in a reverse direction.

The settime of the timer TR2 is preferably slightly longer than that of the timer TR1 so that the yarn ends can be fed back into the spinning rotors after they have been satisfactorily stretched out by the suction effect of the spinning rotors. When the time TR2 counts to the set time, its contacts TR2-1 close to energize a control relay CR2. Therefore, the normally open contacts CR2-1 of the relay CR2 are closed to energize the reverse clutch MC1 while the normally closed contacts CR2-2 are opened to deenergize the winding shaft brake MB2, whereby the take-up rollers 3 and winding rollers 4 are rotated in a reverse direction and the sufficiently untwisted yarn ends can be pushed into the spinning rotors 1.

Also, the contacts CR2-3 of the relay CR2 are closed simultaneously to cause a timer TR11 to start to count to a settime, at which the feed clutch MC3 is

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energized. When the timerTR11 counts to the set time, its contacts TR11-1 are closed to energize a relay CR3, whereby the contacts CR3-1 are closed to energize the feed clutch MC3 while the contacts 5 CR3-2 are opened to deenergize the brake MB1. Thus, the sliver supply to each of the spinning units begins. The sliver 35 is fed by the feeding means to each combing roller 5 by which it is opened into the individual fibers. The individual fibers are then fed 10 into the spinning rotor 1 and twisted into the yarn end fed back in the aforementioned manner into the spinning rotor.

Furthermore, with the closing of the contacts CR2-3, a timer TR12, for setting a time at which the 15 forward clutch MC2 is to be energized simultaneously starts to count to a settime. When the settime of the timerTR12 elapses, its normally open contacts TR12-1 close to energize both a control relay CR4 and a timer TR3 through the normally closed con-20 tacts TR13-1 of a timerTR13forsetting an energization time forthe winding shaft brake and the normally closed contacts DR-2 of the off timer DR of the delayed stop forthe driving motor M. Upon energization of the relay CR4, the normally open contacts 25 CR4-1 close to energize the forward clutch MC2 while the normally closed contacts CR4-2 and CR4-5 open to deenergize both the winding shaft brake MB2 and the reverse clutch MC1. Thus, the take-up rollers 3 and winding rollers 4 are rotated in a for-30 ward direction sothatthe pulling outoftheyarn9 can be effected with propertiming with respect to the connection of the yarn end with the fibers collected in the spinning rotor.

Afterthe forward rotation of both the take-up rol-35 lers 4 starts to pull the yarns 9 out from the spinning rotors, the timer TR3 counts up the settime, when its contacts TR-3 close to energize a control relay CR5. The normally closed contacts CR5-1 are opened simultaneously and therefore the contacts TR1 -1 of 40 the timer TR1 are also opened thereby causing the electromagnets SOLe, which have attracted the upper arms 6e of the yarn holding levers 6c to be deenergized to allow the yarn holding levers 6c to turn into and be maintained by the yarn tension in 45 their yarn sensing position; in which their ends 6d contact the spun yarns 9 during the normal spinning operation.

When either a yarn breakage or an abnormal lowering of yarn tension to a level insufficient to main-50 tain the yarn holding lever 6c in the yarn sensing position occurs in any spinning unit, the lever 6c involved is turned to the yarn holding position as shown in Fig. 2 so that a permanent magnet 6/ mounted on the lever 6c approaches a reed switch 55 PRS. Atthattime, the reed switch PRS is turned on since the normally open contacts CR5-2 have been closed upon energization of the relay CR5. The closing of both the contacts CR5-2 and the reed switch PRS cause an electromagnet SOLf to be energized, 60 whereby a feed clutch (not shown), provided for each spinning unit in association with the fiber feed means 2thereof and normally held in the off state, is turned to the on state to discontinue the fiber supply to the spinning unit involved in the yarn breakage. 65 Although the lever 6c of the yarn holding device 6

in this embodiment of the present invention combines the functions of yarn holding and yarn break sensing, the yarn break sensing may be carried out by a separate device.

70 It will be apparent from the foregoing that according to this invention, the snarling phenomenon which the conventional spinning machines have an avoidably run up against should not occur, resulting in a greatly increased sucess rate in yarn ending at 75 the re-starting of the spinning machine, because, when the spinning machine is stopped, the fiber supply to the spinning rotors is stopped and thereafter, substantially simultaneously with the stopping of the take-up rollers and winding rollers, the yarn 80 ends are held by the corresponding yarn holding devices at a time when they still remain in the region which undergoes the suction effect of the subatmospheric pressure produced in the spinning rotors, which are subsequently stopped, and even after 85 restarting of the spinning machine, the holding of the yarn ends by the corresponding yarn holding devices continues until the subatmospheric pressure produced in the spinning rotors bythe rotation thereof reaches substantially the same level as that 90 produced during normal spinning operation.

Although a single preferred embodiment has been described above, it will be readily understood by those skilled in the art that this invention is applicable to other open end spinning machine having dif-95 ferent constructions. For example, the spinning machine may employ a single electromagnetic clutch in lieu of the reverse and forward clutches MC1 and MC2. Also, the spinning rotors may be driven by a separate motor independent of the motor 100 M, and the feeding of the yarn end in the reverse direction may be carried out by storing up an additional length of yarn between the take-up roller3 and the take-up tube 1 when the spinning machine is stopped and releasing the stored yarn when it is 105 necessary to feed the yarn end in the reverse direction, whereupon the released yarn is sucked into the spinning rotor bythe subatmospheric pressure produced therein.

Claims (1)

110 1. A method for starting and stopping an open end spinning machine including a spinning rotor, a yarn take-up tube extending into said spinning rotor, means for supplying opened fibers into said spinning rotor, means for taking up a yarn through said 115 yarn take-up tube from said spinning rotor, and means for winding the taken-upyarn onto a bobbin: said method comprising the steps of, on stopping said spinning machine, stopping a supply of fibers to said spinning rotor; holding a yarn end resulting 120 from said stopping of the fiber supply at a position « adjacent to a yarn outlet end of said yarn take-up tube before it moves out of said yarn take-up tube while stopping said taking up means and winding ; means; then removing the suction effect of a subat-125 mospheric pressure produced in said spinning rotor, acting on the yarn end; and, on starting said spinning machine, producing the subatmospheric pressure in said spinning rotor under the condition that the yarn end is maintained held; releasing the held 130 yarn end when the subatmospheric pressure

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reaches a sufficient level to prevent the yarn end from being snarled in said yarn take-up tube; rotating said yarn taking up means and winding means in a reverse direction to push the yarn end into the

5 spinning rotor; and rotating said yarn taking up means and winding means in a forward direction after restarting the fiber supply to the spinning rotor.

2. The method according to claim 1, wherein said removing and producing of the suction effect are

10 carried out respectively by stopping and rotating the spinning rotor.

3. The method according to claim 1, wherein said removing and producing of the suction effect are carried out respectively by deenergizing and energiz-

15 ing an intake system disposed outside of the spinning rotor.

4. An apparatus for stopping and starting an open end spinning machine including a spinning rotor associated with means for producing a subat-

20 mospheric pressure therein, a yarn take-up tube extending into said spinning rotor, means for supplying opened fibers into said spinning rotor, means fortaking up a yarn through said yarn take-up tube through said spinning rotor, and means for winding

25 the taken-up yarn onto a bobbin: said apparatus comprising means disposed adjacent to a yarn outlet end of said yarn take-up tube for holding the yarn; and control means for controlling the operation of said yarn holding means, subatmospheric pressure

30 producing means associated with said spinning rotor, fiber supplying means, yarn taking up means and yarn winding means in accordance with a predetermined time sequence so that when the spinning machine is stopped said yarn holding means is

35 operated to hold the yarn end before said subatmospheric pressure producing means becomes inoperative and, on starting, said yarn holding means is operated to release the held yarn therefrom at a time when said subatmospheric pressure pro-

40 ducing means produces sufficient subatmospheric pressure to prevent the yarn end from being snarled in said yarn take-up tube.

5. The apparatus according to claim 4, wherein said subatmospheric pressure producing means

45 comprises a plurality of through holes provided in said spinning rotor.

6. The apparatus according to claim 4, wherein said subatmospheric pressure producing means comprises an air intake system disposed outside of

50 said spinning rotor in air communication with the inside thereof.

7. The apparatus according to any one of claims 4 to 6, wherein said yarn holding means comprises an elastic support block disposed adjacent to the

55 yarn outlet end of said yarn take-up tube, and a yarn holding lever mounted for pivotal motion between a yarn holding position in which said yarn holding lever at its free end engages with said support block to hold the yarn end therebetween, and a yarn

60 releasing position in which said yarn holding lever is disengaged from said support block.

8. The apparatus according to claim 7, wherein said yarn holding lever turns to the yarn holding position past a yarn break sensing position in which said

65 yarn holding lever contacts the spun yarn during normal spinning operation of said spinning machine so as to be held in said yarn break sensing position by the tension of the spun yarn.

9. The apparatus according to claim 7 or claim 8 70 wherein said yarn holding means comprises a permanent magnet capable of attracting said yarn holding lever to bring it into said yarn holding position, and said control means comprises an electromagnet operatively associated with said yarn holding lever 75 so that upon energization thereof said yarn holding lever is attracted by said electromagnet against the attraction of said permanent magnet thereby to turn said yarn holding leverto said yarn releasing position.

80 10. The apparatus according to claim 9, wherein said control means comprises a start pushbutton for starting said spinning machine and accordingly said spinning rotor, and a timer connected in series to said start pushbutton and having contacts connected 85 in parallel to said electromagnet, said contacts being closed to energize said electromagnet when said timer counts up a settime which is so determined that said spinning rotor attains a sufficient speed to produce said sufficient subatmospheric pressure 90 when said settime elapses.

11. A method for starting and stopping an open end spinning machine as claimed in claim 1 and substantially as described.

12. An apparatus for starting and stopping an 95 open end spinning machine as claimed in claim 4

and substantially as described with reference to or as shown by Figs. 2,3A and 3B of the Drawings.

Printed for Her Majesty's Stationery Office byTheTweeddale Press Ltd., Berwick-upon-Tweed, 1980.

Published at the Patent Office, 25 Southampton Buildings, London, WC2A1 AY, from which copies may be obtained.